/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2003-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: SerializerTraceWriter.java,v 1.2.4.1 2005/09/15 08:15:25 suresh_emailid Exp $
 */
package com.sun.org.apache.xml.internal.serializer;

import java.io.IOException;
import java.io.OutputStream;
import java.io.Writer;

/**
 * This class wraps the real writer, it only purpose is to send
 * CHARACTERTOSTREAM events to the trace listener.
 * Each method immediately sends the call to the wrapped writer unchanged, but
 * in addition it collects characters to be issued to a trace listener.
 *
 * In this way the trace
 * listener knows what characters have been written to the output Writer.
 *
 * There may still be differences in what the trace events say is going to the
 * output writer and what is really going there. These differences will be due
 * to the fact that this class is UTF-8 encoding before emiting the trace event
 * and the underlying writer may not be UTF-8 encoding. There may also be
 * encoding differences.  So the main pupose of this class is to provide a
 * resonable facsimile of the true output.
 *
 * @xsl.usage internal
 */
final class SerializerTraceWriter extends Writer implements WriterChain {

  /**
   * The real writer to immediately write to.
   * This reference may be null, in which case nothing is written out, but
   * only the trace events are fired for output.
   */
  private final java.io.Writer m_writer;

  /**
   * The tracer to send events to
   */
  private final SerializerTrace m_tracer;

  /**
   * The size of the internal buffer, just to keep too many
   * events from being sent to the tracer
   */
  private int buf_length;

  /**
   * Internal buffer to collect the characters to go to the trace listener.
   */
  private byte buf[];

  /**
   * How many bytes have been collected and still need to go to trace
   * listener.
   */
  private int count;

  /**
   * Creates or replaces the internal buffer, and makes sure it has a few
   * extra bytes slight overflow of the last UTF8 encoded character.
   */
  private void setBufferSize(int size) {
    buf = new byte[size + 3];
    buf_length = size;
    count = 0;
  }

  /**
   * Constructor.
   * If the writer passed in is null, then this SerializerTraceWriter will
   * only signal trace events of what would have been written to that writer.
   * If the writer passed in is not null then the trace events will mirror
   * what is going to that writer. In this way tools, such as a debugger, can
   * gather information on what is being written out.
   *
   * @param out the Writer to write to (possibly null)
   * @param tracer the tracer to inform that characters are being written
   */
  public SerializerTraceWriter(Writer out, SerializerTrace tracer) {
    m_writer = out;
    m_tracer = tracer;
    setBufferSize(1024);
  }

  /**
   * Flush out the collected characters by sending them to the trace
   * listener.  These characters are never written to the real writer
   * (m_writer) because that has already happened with every method
   * call. This method simple informs the listener of what has already
   * happened.
   */
  private void flushBuffer() throws IOException {

    // Just for tracing purposes
    if (count > 0) {
      char[] chars = new char[count];
      for (int i = 0; i < count; i++) {
        chars[i] = (char) buf[i];
      }

      if (m_tracer != null) {
        m_tracer.fireGenerateEvent(
            SerializerTrace.EVENTTYPE_OUTPUT_CHARACTERS,
            chars,
            0,
            chars.length);
      }

      count = 0;
    }
  }

  /**
   * Flush the internal buffer and flush the Writer
   *
   * @see java.io.Writer#flush()
   */
  public void flush() throws java.io.IOException {
    // send to the real writer
    if (m_writer != null) {
      m_writer.flush();
    }

    // from here on just for tracing purposes
    flushBuffer();
  }

  /**
   * Flush the internal buffer and close the Writer
   *
   * @see java.io.Writer#close()
   */
  public void close() throws java.io.IOException {
    // send to the real writer
    if (m_writer != null) {
      m_writer.close();
    }

    // from here on just for tracing purposes
    flushBuffer();
  }


  /**
   * Write a single character.  The character to be written is contained in
   * the 16 low-order bits of the given integer value; the 16 high-order bits
   * are ignored.
   *
   * <p> Subclasses that intend to support efficient single-character output
   * should override this method.
   *
   * @param c int specifying a character to be written.
   * @throws IOException If an I/O error occurs
   */
  public void write(final int c) throws IOException {
    // send to the real writer
    if (m_writer != null) {
      m_writer.write(c);
    }

    // ---------- from here on just collect for tracing purposes

        /* If we are close to the end of the buffer then flush it.
         * Remember the buffer can hold a few more characters than buf_length
         */
    if (count >= buf_length) {
      flushBuffer();
    }

    if (c < 0x80) {
      buf[count++] = (byte) (c);
    } else if (c < 0x800) {
      buf[count++] = (byte) (0xc0 + (c >> 6));
      buf[count++] = (byte) (0x80 + (c & 0x3f));
    } else {
      buf[count++] = (byte) (0xe0 + (c >> 12));
      buf[count++] = (byte) (0x80 + ((c >> 6) & 0x3f));
      buf[count++] = (byte) (0x80 + (c & 0x3f));
    }
  }

  /**
   * Write a portion of an array of characters.
   *
   * @param chars Array of characters
   * @param start Offset from which to start writing characters
   * @param length Number of characters to write
   * @throws IOException If an I/O error occurs
   */
  public void write(final char chars[], final int start, final int length)
      throws java.io.IOException {
    // send to the real writer
    if (m_writer != null) {
      m_writer.write(chars, start, length);
    }

    // from here on just collect for tracing purposes
    int lengthx3 = (length << 1) + length;

    if (lengthx3 >= buf_length) {

            /* If the request length exceeds the size of the output buffer,
              * flush the output buffer and make the buffer bigger to handle.
              */

      flushBuffer();
      setBufferSize(2 * lengthx3);

    }

    if (lengthx3 > buf_length - count) {
      flushBuffer();
    }

    final int n = length + start;
    for (int i = start; i < n; i++) {
      final char c = chars[i];

      if (c < 0x80) {
        buf[count++] = (byte) (c);
      } else if (c < 0x800) {
        buf[count++] = (byte) (0xc0 + (c >> 6));
        buf[count++] = (byte) (0x80 + (c & 0x3f));
      } else {
        buf[count++] = (byte) (0xe0 + (c >> 12));
        buf[count++] = (byte) (0x80 + ((c >> 6) & 0x3f));
        buf[count++] = (byte) (0x80 + (c & 0x3f));
      }
    }

  }

  /**
   * Write a string.
   *
   * @param s String to be written
   * @throws IOException If an I/O error occurs
   */
  public void write(final String s) throws IOException {
    // send to the real writer
    if (m_writer != null) {
      m_writer.write(s);
    }

    // from here on just collect for tracing purposes
    final int length = s.length();

    // We multiply the length by three since this is the maximum length
    // of the characters that we can put into the buffer.  It is possible
    // for each Unicode character to expand to three bytes.

    int lengthx3 = (length << 1) + length;

    if (lengthx3 >= buf_length) {

            /* If the request length exceeds the size of the output buffer,
              * flush the output buffer and make the buffer bigger to handle.
              */

      flushBuffer();
      setBufferSize(2 * lengthx3);
    }

    if (lengthx3 > buf_length - count) {
      flushBuffer();
    }

    for (int i = 0; i < length; i++) {
      final char c = s.charAt(i);

      if (c < 0x80) {
        buf[count++] = (byte) (c);
      } else if (c < 0x800) {
        buf[count++] = (byte) (0xc0 + (c >> 6));
        buf[count++] = (byte) (0x80 + (c & 0x3f));
      } else {
        buf[count++] = (byte) (0xe0 + (c >> 12));
        buf[count++] = (byte) (0x80 + ((c >> 6) & 0x3f));
        buf[count++] = (byte) (0x80 + (c & 0x3f));
      }
    }
  }

  /**
   * Get the writer that this one directly wraps.
   */
  public Writer getWriter() {
    return m_writer;
  }

  /**
   * Get the OutputStream that is the at the end of the
   * chain of writers.
   */
  public OutputStream getOutputStream() {
    OutputStream retval = null;
    if (m_writer instanceof WriterChain) {
      retval = ((WriterChain) m_writer).getOutputStream();
    }
    return retval;
  }
}
